For research, I always recommend starting simple with Excel to get familiar with numbers and stats. Python IMO should be the next step. I wouldn't execute with either one. IMO they're best suited for prototyping.
Random thoughts,
If you are going to use python, Dr. Howard Bandy has some good books that include python code (and AmiBroker code). I have no interest in using python. I use Java and will eventually move to Kotlin (a JVM language). That said, C# is a great choice since many platforms use it. Ninja, MultiCharts.net, Wealth Lab Pro, others?
Python is a good choice to cobble things together and/or if your platform of choice uses it.
Java and C# are good if writing high-performance professional applications.
I would pick platforms/languages that have lots of example code available for free. I like the idea of being able to download the code in Stocks & Commodities mag and load it into a platform and see what it does.
I've never programmed Excel or MATLAB so I can't comment.
Have fun